Safety pilot light



Aug. 27, 1935. F. A. GAUGER SAFETY PILOT LIGHT Original Filed April 5,1930 2 Sheets-Sheet l ,6 211 ATTORNEY Aug. 27, 1935. F. A. GAUGER SAFETYPILOT LIGHT 2 Sheets-Sheet 2 Original Filed April 5, 1930 ATTORNEYPatented Aug. 27, 1935 UNITED STATES SAFETY PILOT LIGHT Frank A. Gauger,Milwaukee, Wis, assignor to Milwaukee Gas Specialty Company, acorporation 6: Wisconsin Original application April 5, 1930, Serial No.

Divided and this application Februmy 6, 1933, Serial No. 655,418

Claims. (C1. 158-1171) This invention relates to a safety pilot light.This application is a division ofmy copending application Ser. No,441,836, filed Apr. 5, 1930, for Safety pilot light. 5 Objects of thisinvention are to provide a novel form of safety pilot light which may bemounted wholly within a combustion chamber, such, for example, as thecombustion chamber of a furnace or other apparatus, which is so madethat it will not respond to the general temperature or the radiated heatin the combustion chamber, but will respond only to the heat generatedby the pilot light itself, such pilot light being so made and associatedwith a thermostatic member that II in the specific construction aportion oi the flame of the pilot light plays directly upon thethermostatic member.

Further objects are to provide a novel form of pilot light, combined asa unit with a thermostatic member, which is so constructed that thethermostatic member is directly carried by the pilot light and forms aunitary portiontherewith, in which the supporting structure for thecombined pilot light. and thermostatic member is in reality the supplypipe and supply nozzle for the pilot light, and in which theconstruction is such that the entire pilot light and thermostaticcontrol device may be bodily lifted from the supply pipe and supplynozzle, for repair or inspection, in a very simple and easy manner.

Further objects are to provide a novel form of safety pilot light inwhich the thermostatic member is quickly responsive, and is preferablyso made that a positive stop is provided for arrestlog the motion of themovable portion of such' thermostatic member at one point in its travelto thus prevent excessive pressure being exerted upon the controlmember, and to so construct the thermostatic member and so associate itwith the 40 pilot light that the maximum speed of response is obtained.

Further objects are to provide a, novel form of safety pilot light whichis mounted, as pointed out above, wholly within the combustion chamher,but which, nevertheless, operates a control member located outside ofthe heated zone of the combustion chamber and protected from excessiveheat, and preferably located within the incoming stream of secondaryair, so that it is maintained in a fairly cool condition at all timesand irrespective of the temperature within the provided with a controlvalve ll.

'pipe extends upwardly, as indicated at 12, and

an integral structure comprising the balanced U-tube pilot light, thethermostatic member, and the control member operated thereby, and to soassociate these parts that there is an imperfect thermal conductivitypath between the pilot light 5 and the supply nozzle, so that the supplynozzle does not become excessively heated, thereby avoidingcarbonization and choking of such supsimple, which is easy to positionand remove,

which is rugged, and which is not likely to get out of order. s r 15Embodiments of the invention are shown in the accompanying drawings, inwhich:

Figure 1 is a sectional view through a portion of a furnace and througha part of the safety pilot light. 20

Figure 2 is an enlarged sectional view on the line 2-2 of Figure 1.

Figure 3 is an enlarged sectional view on the line 3--3 of Figure 1.

Figure 4 is a view corresponding to Figure 1 as showing a diilerent formof theapparatus.

Figure 5 is an enlarged sectional view on the line 5--5 of Figure 4.

Before entering the detailed discussion of this invention, it is to benoted that the pilot light is adapted to be positioned wholly within thecombustion chamber, and is provided with a control member which islocated outside of the combustion chamber, or at all events, outside ofthe heated zone of such chamber, and that the con- 35 trol member may beeither an electrical control member or may be so constructed that itcontrols through the medium of gas pressure, or in a similar manner.

Referring to Figures 1 to 3 which show the first 0 form -of theinvention, it is to be noted that a gas furnace has been indicated asprovided with a casing I provided with a transverse portion 2, andforming a combustion chamber 3. A main burner ,4 is located within thecombustion chama I her and is supplied from the main gas supply manifold5, a valve 6 being provided between the manifold and the mixing tube Iof the burner. The secondary air enters the space indicated at 8 andpasses upwardly through the duct provided 50 by the auxiliary casing 9.

It is to be noted that a branch supply pipe l0 extends downwardly fromthe manifold 5. and is This branch provides a support for the safetypilot light. The portion l2 preferably is carried by a shoulderedfitting l3, and is provided with a small supply nozzle I 4 at its upperend. I

The safety pilot light comprises a U-burner having two main passagewaysI5 and I6 which communicate by way of the intermediate passageway l'l.All of these passageways are formed in an integral casting I8 and it ispreferable to provide a plurality of openings l9, which are in realitythe openings at which the flames are formed. Preferably one opening I9is on the upper side of the casting of the U-burner, as shown in Figure1, and is located practically directly beneath the curved portion of thethermostatic member 26. This thermostatic member is locked to thecasting l8 by means of a bolt 2| or other suitable member. This bolt hasits head located below the free arm of the thermostatic member andprovides a stop for such free arm to limit its downward motion. The freearm is provided with a substantially non-expanding metal projecting arm22 which is riveted thereto or otherwise secured. This arm 22 isprovided with an adjusting screw or contact member 23, which, when inadjusted position, is locked by means of the lock nut 24.

Returning to the U-burner of the safety pilot light, it will be seenthat the casting I8 is bored and threaded to receive the Venturi inserttube 25 and the insert bushing 25, which latter receives the supplynozzle Hi and thus accurately aligns the nozzle with the Venturi tube25. As a matter of fact, the holes for the Venturi tube 25 and thebushing 26 maybe readily bored out in the casing as they are inalignment, and thus it is a simple matter to bore and thread such holes.At this point it is to be particularly noted that there is only asliding fit, which is fairly loose, between the supply nozzle M and thebushing 26. Consequently the thermal conductivity between the casting E8of the U-burner and the supply nozzle I l is very poor. The result ofthis construction is that the supply nozzle is only slightly heated evenwhen the apparatus is in continuous operation, and consequentlycarbonization and choking of the nozzle cannot occur. The casting i8 isrigidly carried by a sleeve or tube 2'! which forms an integral portionthereof and whose lower end is threaded into a casing 28 also formed asa casting. This casing 28 is provided with an apertured lip 29, which isslidably carried by the supply pipe i2, preferably fitting over thecylindrical portion of the fitting i3 and resting upon the lowershouldered portion of such fitting. The construction is such, therefore,that the U-burner of the safety pilot light is in reality carried by thesupply pipe, the upper end of the safety pilot light fitting over thesupply nozzle and the lower end being slidably carried and supported bythe supply pipe.

Preferably the lower portion of the casing 28 is closed by means of aninsulating bottom plate 30. This insulating bottom plate 30 carries astationary contact member 3| and a U-shaped, movable, spring contactmember 32. The movable contact member 32 is most clearly shown in Figure3, and it will be seen that such member is provided with a lip or ear 33underhanging the stationary contact 3| and with a lip or ear 34',

which is readily fastenedto the insulating base plate 30. Suitablebinding posts 34 are connected to the contacts and also are connected tothe conductors of a cable 35, see Figures 1 and 2. The cable 35 extendsto the main control valve in the usual manner, so that when the contactsare closed, the valve is permitted to operate, but when the contacts areopened, due to the action of the material to thus electrically insulatethe movable contact member from the metal rod.

From actual trials it has been foundthat there is a tendency forparticles of dust to be drawn downwardly into the passageway l6.Obviously, irrespective of the minuteness of these particles, they willultimately somewhat clog' or pack around the rod 35 if the rod is notprotected therefrom. Consequently, a small, protecting sleeve or tube 38loosely surrounds the rod 36 and is preferably threaded into the maincasting iii of the U-burner of the pilot light, as shown in Figure 1.This sleeve 38 is relatively small and does not close the passageway I6. Consequently air can flow between such tube 38 and the walls of thepassageway it, and thus provide an adequate supply for the U-burner ofthe pilot light. However, inasmuch as the tube 38 projects upwardly aconsiderable distance, preferably to the top of the casting is, it isclear that the rod is guarded from accumulation of dust particlesentrained with the air.

From the description thus far given, it is apparent that a balancedU-tube safety pilot light has been provided by this invention which isso made that it may be wholly mounted within the combustion chamber of afurnace or similar device, and which cannot be extinguished by explosons or sudden variations of pressure occurring within such combustionchamber.

It is also apparent that very simple and easily constructed controlmeans are provided and associated with the safety pilot light, and thatexcessive displacement of the elements of this control member isprevented by the manner in which the thermostatic apparatus isconstructed, as previously described.

Although the operation is apparent from the previous description, it isbelieved a brief statement thereof is desirable.

When the pilot light is in operation, the thermostatic member 20 isheated and the arm 22 is moved upwardly, thus allowing the rod 36 tomove upwardly and allowing closing of the contacts. As previouslystated, any explosion, due to lighting or extinguishing of the mainburner, produces the same pressure upon the opposite ends of theU-shaped burner of the pilot light and does not,

therefore, tend to extinguish such pilot light. The thermostatic memberis so constructed that as long as it is heated, preferably directly bythe pilot light, it will maintain the contacts closed. However, if thepilot light is extinguished for any reason, the thermostatic member thenmoves the arm 22 downwardly, forcing the rod 36 downwardly, and opensthe contacts. This, in accordance with the well known practice, opensthe circuit of the main supply valve and prevents supply of fuel to themain burner.

' The form of the invention shown in Figure 4 is substantially the sameas that shown in Figure l, with, however, the exception that the controlmember is differently constructed. This control member operates acontrol valve by gas pressure in a well known manner.

The control member, in this second form of the invention, is the onlydifferently constructed portion of the apparatus from that previously described, and consequently such control member alone need be described.

This control member consists of a fitting 39 which carries a valve seat40 adapted to cooperate with a ball valve ll. This ball valve is urgedtowards closed position by means of the helical compression spring 42,and is forced open by means or the rod 36 previously described. The.

lower portion of the fitting 39 is closed by a plug t3 screwed thereintoand carrying the compression spring 2. The supply pipe i2, similar tothat previously described, is provided with a fitting M, which replacesthe fitting 13, see Figure 1. The fitting it and the fitting 39 areprovided with list faces, which may, take any shape. In Figure 4 thelace oi the fitting 46 is shown. These faces are drawn together, andconsequently the fittings M and 89 are joined by means bolts or screws45, preierably a washer l of paper, iiber, or similar material beinginterposed between such laces to insure a gas-tight joint.

A control pipe t'l leads outwardly to the control valve (not shown) fromthe fitting 3! and communicates with the space above the valve ll bymeans of a small duct 48. The interior of the supply pipe 2 communicateswith the space below the valve M by means of a small duct 49. It isclear, thereforethat when the valve 4! is seated, which would correspondto the condition when the pilot light is lighted, no gas pressure istransmitted to the pipe ill post the control member, and, consequently,the control valve for the main burner is allowed to operate, asrequired, in the usual and well known manner. However, when the valve llis displaced by the thermostatic member, gas pressure is communicated tothe pipe 47 and the main control valve (not shown) is prevented fromoperating, and, consequently, no gas can pass to the main burner.

It is to be noted that the pipe to, which connects with the supply pipeI2, is to be connected to the supply mains ahead oi the automaticcontrol valve (not shown) for the main burner, in the usual manner.

It is to be noted particularly that no studios box or packing isrequired for the rodas, as any gas that leaks past this rod in thenormal operation of the apparatus is entrained with the incoming air forthe pilot burner and consequently is consumed in the pilot burner. Thegas passing the rod 36 is drawn through the port M and is therebycarried along with the mixture to the pilot burner.

It will be seen that means are provided intermediate the control member,whether it takes the form of the electric contacts shown in Figure 1 orthe combustion chamber, and that this safety pilot light is not causedto operate by the general temperature or heat within the combustionchambar, but is responsive only to the heat generated by the pilotlight.

It will also be seen that a very simple type of safety pilot light hasbeen provided in each form of the invention which is easy to construct,which is substantially foolproof, which is positive in its operation,and which is truly reliable.

Although this inventionhas been described in considerable detail, it isto be understood that such description is intended as illustrativerather than limiting, as the invention may be variously embodied and isto be interpreted as claimed.

I claim: l. A unitary pilot light and thermostatic pilot switch devicecomprising. a main burner, a U-shaped pilot light for said main burnerconstituting a Bunsen burner, a fuel supply pipe for said pilot light, athermostatic member carried by said pilot light and responsive thereto,a control device mounted as a rigid unit with. said pilot light andoperated by said thermostatic member, said pilot light,-saidthermostatic member and said control device forming a unitary structuresupported from said fuel supply pipe and readily removable therefrom bya sliding motion longitudinally of said supply pipe.

2. A pilot light comprising a supporting fuel supply member providedwith a fuel nozzle, a. U-tube body portion, one of its main arms beingan air inlet and the other main am being a mii ture outlet, said fuelsupply member forming the support for said body portion and said fuelnozzle having poor thermal connection with said body portion to preventcarbonization at the nozzle, and a thermostatic member carried by thesaid main arm forming the mixture outlet, said thermostatic member beingresponsive to saidpilot light, and control means'actuated by saidthermostatic member.

3. A pilot light having a body portion provided with an air inlet and afuel outlet, a fuel supply pipe having a nozzle opening into said bodyportion, said fuel supply pipe extending downwardly from the nozzle,supporting means rigidly connected with said body portion and extendingdownwardly from said body portion, said means being supported by saidfuel supply pipe at a point remote from and below said nozzle andsupporting said body portion, a thermostatic member carried by andresponsive to said pilot light. and control means including meansconnecting the same to said thermostatic member and spaced downwardlytherefrom and supported as a unit from said fuel supply pipe with saidpilot light.

4. A pilot light having a body portion provided with an air inlet and a.fuel outlet, said fuel outlet constituting an extension projectinglaterally from said air inlet, and said air inlet and said fuel outletforming a U-burner, a fuel supply pipe having a nozzle opening into saidbody portion. said fuel supply pipe extending downwardly from thenozzle, supporting means rigidly connected with said body portion andextending downwardly from said body portion, said means being re=movably supported by said fuel supply pipe and supporting said bodyportion at a point remote from and below said nozzle, a thermostaticmember carried by the laterally projecting extension of said pilot lightand responsive to said pilot light, and a control device supported iromsaid body portion at a point spaced downwardly from said pilot light,said control device being operatively connected to said thermostaticmember.

5. In a device of the class'described, a casing, a main burner locatedwithin said casing, a fuel sup- 5 ply, a fuel standard nozzle connectedto said fuel supply, a 'U-tube Bunsen pilot light positioned within saidcasing and drawing its primary and secondary air from within said casingonly, a

thermostatic member carried by said pilot light and responsive thereto,and a control device carried as a unit with said pilot light, said pilotlight being detachabiy supported by said fuel standard nozzle and beingreadily lifted therefrom as a unit with said control device withoutdisturbing the adjustment of said thermostatic member.

FRANK A. GAUGER.

